Is there a rationale to how Hemalurgic powers are distributed? I tried to look for a system, but they seem rather randomly distributed. For example, the spike which steals Allomantic powers for a particular quadrant is not always in one particular spot.
That is correct, it’s not always in one particular spot. None of them are. I used as my model on this magic system the concept of acupuncture and pressure points. Placing a Hemalurgic spike is a very delicate and specific art. Imagine there being a different overlay on a human body, like a new network of nerves, representing lines, points, and ‘veins’ of the soul’s spiritual makeup.
What is happening with Hemalurgy, essentially, is that you’re driving a spike through a specific point on a person’s body and ripping off a piece of their soul. It sticks to the spike on the Spiritual Realm. Then, you place that spike on someone else in a specific place (not exactly the same place, but on the right spiritual pressure point) and ‘hot wire’ the spirit to give it Hemalurgy or Feruchemy. It’s like you’re fooling the spiritual DNA, creating a work-around. Or, in some cases, changing the spirit to look like something else, which has the immediate effect of distorting the body and transforming it into a new creature.
Hemalurgy is a very brutal way of making changes like this, though, so it often has monstrous effects. (Like with the koloss.) And in most cases, it leaves a kind of ‘hole’ in the spirit’s natural defenses, which is how Ruin was able to touch the souls of Hemalurgists directly.
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